The Venerable Denon DL-103

Over the years, much has been written about the venerable Denon DL-103 and its variants. As originally designed in 1964, the cartridge was intended for NHK broadcast studios in Japan. The NHK turntables in the 1960s were Denon DN-302F direct drive units with heavy 12” Denon DA-302 tonearms (with high effective mass, in the range of 30 to 32 grams). See Denon history.

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Denon DL-103

To clarify the relationship between a heavy tonearm and a low compliance cartridge like the DL-103, an automotive analogy can shed light on how these two components operate together. Cars and trucks both use springs to stabilize vehicle ride on different road surfaces. When vehicles ride over uneven surfaces, the springs adjust the distance between the road, wheels, and the vehicle body. Cars weigh less than trucks so they have light springs and heavy trucks have heavy springs.

When you think of a tonearm as the car or truck and the cartridge compliance as the spring, what would happen if you installed heavy truck springs on a light weight passenger car? The ride would be unbearably rough. The slightest road bump would feel like you just hit a massive pot hole.

Denon DA-302 tonearm, effective length 282mm

So in this analogy, the car's ride performance is similar to the tonearm/cartridge tracking performance for vinyl playback. Therefore, it makes sense to "mass-up" the tonearm by adding weight at both ends (not easily done on some arms). Using a basic effective mass calculator (link below), the Micro Seiki MA-505 has an effective mass of 14.5 grams. It needs another ~16 grams to achieve a new effective mass of about 30 grams. To add 16 grams to this tonearm, more weight at the headshell and more counterweight has to be installed.

In this experiment, a metal body was used adding 15 grams (25 grams total combined headshell, screws, wires, body, and cartridge), and a heavier redesigned counterweight with a lower center of gravity to reduce inertia added about 120 grams. Using the same recommended tracking force of 2.5 grams, the listening tests were very successful and the results were obvious and impressive with the unmodified original conical stylus. Adding weight to the tonearm can be a low cost (or no cost) modification to test for improved acoustics on an unmodified Denon 103 cartridge.

Denon DN-302F

Once the tonearm and cartridge are set up properly with the right amount of effective mass, the other area to consider upgrading is the stylus and cantilever. Replacing the conical stylus and the aluminum cantilever with a line contact, shibata, or simple elliptical type on a boron or ruby cantilever will provide another significant performance boost. The caveat here is that the setup (ie. VTA, VTF, azimuth, etc.) will need to be much more precise to hear the higher performance configuration. The stylus and cantilever upgrade can cost $500 or more. For people with a DL-103 that need to be re-tipped (as opposed to re-tipping a new DL-103), the cost is probably worth it, as the improved  acoustics will be on par with some cartridges in the $1,500 to $2,500 price range. You will need to listen for yourself.

The MA-505 | Denon 103 Project

The Denon DL-103 enjoys a long history and cult-like following of people that love to hot rod this moving coil cartridge. Much has been written on how to modify the cartridge and acoustic performance reviews attest to the improvements. But, what modifications make the most sense? Practically speaking, it may not make sense to spend more than $1,000 on 103 modifications when there may be better existing cartridges from manufacturers like Audio Technica or Ortofon.

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Denon DL-103R with sterling silver shell

To begin, let’s proceed with a few project assumptions: 1. it doesn’t make a lot of sense to spend more than $1,000 on modifications so your Denon 103 will sound like a a $1,000 cartridge. It makes more sense to spend $500 to $750 on modifications so your cartridge will sound like a $2,500 cartridge. 2. Adding effective mass to the tonearm is needed with any type of modification to the 103. 3. Some degree of potting (internal gluing) is recommended. 4. Upgrading the stylus (and possibly the cantilever) is just as important as using the right effective mass. 5. Everything else is probably less critical.

The main purpose of this project is to explore upgrade and modification options while keeping the cost under $500 and realize acoustic performance better than or equal to any (MC or MM) cartridge costing at least $1,500.

First, we need to increase the effective mass of Micro Seiki MA-505 tonearm from 14.5 grams to about 30-32 grams. An effective mass calculator can be downloaded here: https://www.audio-creative.nl/wp-content/uploads/Calculator-effective-tonearm-mass.xlsx

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MA-505 tonearm with heavier lower CG counterweight

Counterweight
To increase the effective mass and accommodate the extra cartridge body weight, the MA-505 needs much more counterweight. This new design replaces the factory counterweight and provides a lower center of gravity with increased mass located closer to the pivot point to reduce inertia. The holder is available on Shapeways for about $12 USD and can be found here: Shapeways. A 2.25” stainless steel rod (OD .75”) is needed to provide about 120 grams of counterweight. Rods are available at Online Metals for about $8 USD.

Body
Next, the heavier body adds about 14 to 15 grams of mass. To get an idea of the required tonearm balancing, three US 5¢ coins will approximate 15 grams. To build the body, we used a CAD file on GrabCAD and 3D printed it in bronze at Shapeways for about $75. The tool list and the CAD file can be downloaded here: https://grabcad.com/library/denon-103-body-1

103 Modifications
A 103R was used for this project because of the lower electrical impedance of 14 ohms ±20% (as opposed to the standard 103 with 40 ohms). The simple modifications made to the Denon DL-103R included a installing a new line contact stylus and a hardened tapered aluminum cantilever for about $375.

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Denon DL-103R cartridge with copper open-air shell

Estimated Cost Summary*
103 Retipping $375 (Nude 5/75 line contact, hardened tapered aluminum cantilever)
103 Body $75 (plus ~3 hours of machining and tapping)
Counterweight $20
Total $470

*Estimated costs do not include screws, tools, taxes, or shipping charges.

As Tested | Listening Evaluations
This is where the rubber meets the road (in keeping with the earlier analogy). After the recommended break-in period of 50 hours, the listening tests began.

For the listening tests, the following cartridges were used:
1. Audio Technica AT33PTG/II
2. Ortofon Kontrpunkt b (upgraded by Joseph Long with a Fritz Gyger S stylus and a boron cantilever)

Reference Albums
1. Pink Floyd, Dark Side of the Moon (1979 pressing)
2. Dire Straits, Brothers in Arms (Mobile Fidelity Sound Lab)
3. Joni Mitchell's Court and Spark (Nautilus Records UNAU 11)
4. David Crosby, If I Could Only Remember My Name (Mobile Fidelity Sound Lab)

Turntable
Micro Seiki DDX-1000 with an MA-505 tonearm and modified counterweight, oil damper (45k CST silicone oil), and custom AST arm stabilizer for the AX-1 armboard.

Micro Seiki DDX-1000 with an upgraded Audio Technica AT-1010 tonearm (upgraded by Angus MacDonald, UK), and custom AST arm stabilizer for the AX-1 armboard.

Summary
(to be updated)

If you would like to share your experience or make suggestions on 103 performance improvements, please click the feedback button.